1. Field of the Invention
The present invention relates to bands which decrease the wear around the outside diameter of oil or gas well drill pipes, the joints of which typically have welded hardbands adjacent thereto.
2. Description of the Related Art
The methods for drilling and casing oil and gas wells have evolved considerably in recent years. In particular, the introduction of horizontal drilling tools and techniques, as well as the exploitation of lower yield production zones have placed new demands on oil and gas well service providers responsible for completing wells for production.
No matter what the medium, no matter what the depth and no matter what the technique, all wells involve the installation of casing and, in some cases, sleeving, which results in long segments of joined piping (in some instances three to five thousand feet or more) which is formed by forming joints in much-shorter segments of pipe, usually about thirty (30) feet.
Extended-reach (ERD) and other critical projects exceed the capabilities of conventional steel drillstring assemblies. Alternative materials and advanced technologies are being evaluated to expand the ERD envelope. Titanium has been used, and solutions under development incorporate a new ultra-high-strength steel. Aluminum is also becoming a material of choice. For one, drilling contractors find that aluminum drill pipe can cut their drilling costs, with greater advantage occurring at increasing drilling depths.
While the substitution of aluminum for steel drill pipe can result in operating cost savings, maximum economic gains can be realized by properly matching the aluminum drill pipe with other related drilling project factors, such as hardband selection. Currently, the application of wear bands by welding, thermal spray or laser cladding etc. involves heating and/or melting of the drill pipe surface. Heating the pipe can degrade its' mechanical properties, particularly age-hardened aluminum drill pipe. In addition, these products are metallurgically bonded, and so they can only be removed by cutting them off the drill pipe. Thus, current wear band technology may damage the drill pipe during application, and does damage the pipe when removed.
Accordingly, proper hardband selection, application and maintenance are essential to successfully and safely drilling deep projects. The hardband designer must balance the often-conflicting traits of high hardness to protect the tool joint, low casing wear properties and cracking tendencies. The correct hardband solution can maximize drillstring life by protecting the tool joints from excessive wear, minimize wear of the intermediate casing strings in the well (essential to maintain pressure integrity of the well and ensure a safe operating environment) and reduce the friction coefficient between the drill pipe and the wellbore, which in turn reduces the torque and drag forces acting on the drillstring. Furthermore, although the performance of a particular hardbanding material may be a primary reason for selecting or rejecting a material, there are secondary considerations including but not limited to field experience, availability of application and reapplication, ability to be field-applied in a consistent manner, and cost.
However, even when applying the above factors, wear band/hardband applications are still performed using a welding or thermal spray process. Although the hardband materials can be specially designed to maximize the drillstring life, state of the art wear hands cannot be applied or removed without at least minor damage and/or dimension changes to the drill pipe and significant labor requirements. In the instant invention, this welding is replaced as further described herein.